Apple has officially acknowledged that users could still experience issues with the third-generation butterfly keyboards in newer Mac notebooks.

In a statement to The Wall Street Journal’s Joanna Stern, an Apple spokesperson said the company is aware that “a small number of users are having issues with their third-generation butterfly keyboard and for that we are sorry.”

The company, however, added that “the vast majority of Mac notebook customers are having a positive experience with the new keyboard.”

Users who have been following the Apple or Mac blogosphere for any length of time will probably familiar with the issue’s symptoms.

Quite a few users have reported that their butterfly keyboards experience “sticky key” issues that prevent some key presses from registering. On the other end of the spectrum, other reports suggest that some butterfly keyboards have a “double key press” issue.

Both issues can likely be tied to the butterfly keyboard mechanism themselves. As far as the root cause, it’s not entirely clear. Many people attribute the problems to dust or debris, but others have suggested that long-term exposure to heat could also play a role.

With the third-generation butterfly keyboard, seen in the 2018 MacBook Air and MacBook Pro with Touch Bar models, Apple introduced a silicone membrane to mitigate problems caused by dust. Ostensibly, that membrane was meant to make the keyboard “quieter,” but it’s also a fairly obvious dust-prevention measure (even if Apple has never acknowledged that publicly).

Apple has launched a service program that offers free repairs for impacted machines — but only for 2015-2017 MacBook or 2016-2017 MacBook Pro models. That means models with third-generation butterfly keyboards aren’t covered currently (although many of them are likely still under warranty).

On the other hand, it’s looking more and more likely that Apple will eventually launch a repair program for 2018 MacBook Air and 2018 MacBook Pro models. Acknowleding the issue publicly is a step in that direction.

It’s important to note that not all butterfly keyboards will come down with the problem — despite what social media, tech YouTubers and Apple forums would have you think.

Still, while it’s impossible to know how widespread the issue is, due to a lack of hard numbers or statistics released by Apple or third-party repair shops, the keyboard issues are still common enough to warrant concern among Apple users.

Users impacted by keyboard issues should contact Apple or an Apple Authorized Service Provider for support. 2018 MacBook Air or MacBook Pro users should still be under warranty, while everyone else is probably covered under the repair program.